Ten percent of kids defy gender norms before age 11, a new study published in the journal Pediatrics found. Boys considered "girlie," because of their activity choices and interests, and girls deemed "boyish" are more likely to face abuse -- both physical and sexual -- and experience post-traumatic stress disorder by early adulthood. According to USA Today, parents or other adults in the home were mostly responsible for the abuse.

Andrea Roberts, lead author of the study and research associate in the department of society, human development and health at the Harvard School of Public Health, told USA Today that children under 11 are very likely to display behavior that has nothing to do with their future sexual orientation -- of 9,000 young adults studied, 85% of the 10% considered gender-non-conforming children identified as heterosexual.

Researchers asked a sample of adults ages 17 to 27 to fill out questionnaires about their childhood experiences probing topics "including favorite toys and games, whether they took male or female roles in pretend play, and media characters they imitated and admired," USA Today reports.

Two years later, the respondents were asked about any abuse they experienced and were also screened for PTSD.

While girls who were considered non-conforming were at 60% greater risk for sexual abuse than conforming girls, boys who acted outside of gender norms faced three times the risk over their conforming counterparts. Both non-conforming men and women showed rates of PTSD almost double those considered "normal."

Roberts tells WebMD that the reason these kids are at higher risk for abuse and PTSD is unknown, and more research must be done to determine. "Parents may be uncomfortable with their child's gender expression and may think that parenting can change behaviors, so they may become harsher," she said. "Some parents think kids who are non-conforming will grow up to be a gay or lesbian, and if they are not comfortable with this, they may think they can change a kid's future."

Psychotherapist Robin Friedman points out on WebMD that the definition of "non-conforming" is ever-changing because of how rapidly gender roles are shifting in society. She lists stay-at-home dads and CEO moms as examples. Recently, HuffPost senior columnist, Lisa Belkin, questioned if we should retire the word "wife" considering its connotation and that, in this day and age, men and women should be equals in a marriage.

But the results of this study show that many households still believe in traditional roles and are not sure how to respond when faced with gender non-conformity. "Some parents may respond with love and support, others may respond with concern, or with alarm bells ringing, while others may respond with anger, or emotional or physical abuse," Friedman says.

Commenters on "Overheard on CNN.com" weren't surprised by the study's results. One said that we didn't need a study or multiple Ph.D.s to tell us what we already knew. "'If you're not like the rest of us, we'll beat you up.' We learned that in elementary school," the guest wrote.

Other readers wondered whether the implications of this study will turn "normal" childhood behavior into a disorder. Contributor mwhite5990 wrote:

"I really hope they don't start to think that girls that like sports now have a psychological disorder. When I was a kid I loved to play with Barbies, dress up, but I also loved to go outside and play sports and play video games. I think it is healthy for kids to show typical signs of both genders. Most of my friends went through a 'tomboy' phase. And from what I know, all of us are straight women. If a girl wants to play sports or a boy wants to be a dancer, let him, don't just assume he/she is gay. Gender roles are created by society. In short, let kids be kids and have fun."

"If kids or teens are in a situation where families are abusive or very critical, they will find other people in the community when they are on their own and grown up. These kids should not feel like they are freaks or abnormal," he told WebMD.